U.S. patent application number 10/451181 was filed with the patent office on 2004-03-11 for method and associated device for storing teletext sub-pages.
Invention is credited to Albella, Arnaud, Crespo, Thierry.
Application Number | 20040046892 10/451181 |
Document ID | / |
Family ID | 8858065 |
Filed Date | 2004-03-11 |
United States Patent
Application |
20040046892 |
Kind Code |
A1 |
Crespo, Thierry ; et
al. |
March 11, 2004 |
Method and associated device for storing teletext sub-pages
Abstract
A method for the storage of sub-pages of a teletext service
comprises a page (Y0) to be stored, said page (Y0) to be stored
comprising at least one sub-page. A desired sub-page is stored (E2,
E4) and, as the case may be, sub-pages neighboring the desired
sub-page are stored (E5) until a maximum number of stored sub-pages
(MAXY0) is reached or until a limit number (NB_LIMY0) of sub-pages
of the page to be stored is reached. In one example, the desired
sub-page is the rank 1 sub-page of the page to be stored, and the
neighboring sub-pages, if any, are the following sub-pages. A user
thus has direct access to the start of the information contained in
the page to be stored. In another example, the desired page is a
rank X0 sub-page requested by a user, and the sub-pages neighboring
the desired sub-pages are pages with ranks 1, X0+1, X0-1, etc.
Inventors: |
Crespo, Thierry; (Trets,
FR) ; Albella, Arnaud; (Aix en Provence, FR) |
Correspondence
Address: |
Christopher F Regan
Allen Dyer Doppelt Milbrath & Gilchrist
P O Box 3791
Orlando
FL
32802-3791
US
|
Family ID: |
8858065 |
Appl. No.: |
10/451181 |
Filed: |
October 20, 2003 |
PCT Filed: |
December 13, 2001 |
PCT NO: |
PCT/FR01/03972 |
Current U.S.
Class: |
348/468 ;
348/553; 348/714; 348/E7.033 |
Current CPC
Class: |
H04N 7/0882
20130101 |
Class at
Publication: |
348/468 ;
348/714; 348/553 |
International
Class: |
H04N 007/00; H04N
011/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 5, 2001 |
FR |
01/15706 |
Claims
What is claimed is:
1. A method for the storage of sub-pages of a teletext service
comprising at least one page (Y0) to be stored, said page (Y0) to
be stored comprising at least one sub-page, wherein: a desired
sub-page is stored (E2, E4), and as the case may be, sub-pages
neighboring the desired sub-page are stored (E5) until a maximum
number of stored sub-pages (MAXY0) is reached or until a limit
number (NB_LIMY0) of sub-pages of the page to be stored is
reached.
2. A method according to claim 1, wherein the desired sub-page is a
rank 1 sub-page of the page (Y0) to be stored, and the sub-pages
neighboring the desired sub-page are the sub-pages with ranks
closest to one.
3. A method according to claim 1, wherein the desired sub-page is a
rank X0 sub-page requested by a user, and the sub-pages neighboring
the desired sub-pages are pages (X0-1, X0-2, . . . ) immediately
preceding the desired sub-page and/or sub-pages (X0+1, X0+2, . . .
) immediately following the desired sub-page.
4. A method according to one of the claims 1 to 3, wherein: the
teletext service comprises several pages to be stored, each page
comprising at least one sub-page, for each page to be stored, a
desired sub-page is stored, this sub-page being either a rank 1
sub-page or a sub-page requested by the user, for each page to be
stored, sub-pages neighboring the desired sub-page are stored until
a maximum number of stored sub-pages (MAXY0) of the page to be
stored is reached or until a limit number (NB_LIMY0) of sub-pages
of the page to be stored is reached.
5. A method according to claim 4, wherein the pages to be stored
are pages close to the desired page.
6. A method according to claim 4, wherein two pages to be stored
have different limit numbers NB_LIMY of sub-pages.
7. A method according to claim 4, wherein two pages to be stored
have different maximum numbers (MAXY) of stored sub-pages.
8. A method according to claim 1, wherein, to store the page (Y0)
to be stored, the following steps are carried out: E1: the
initialization of a counter (NB_SS_PGES=0) to count the number of
sub-pages stored, E2: the storage of a rank 1 sub-page of the page
(Y0) to be stored, and the updating of the counter
(NB_SS_PGES=NB_SS_PGES+1), E4 the storage of a desired rank X0
sub-page of the page (Y0) to be stored, and the updating of the
counter (NB_SS_PGES=NB_SS_PGES+1), the step E4 being carried out
only if the rank X0 of the desired page is different from 1, and
E5: the storage of sub-pages neighboring the desired rank X0
sub-page and the updating of the counter, the step E5 being
repeated until the counter has reached a maximum number of stored
sub-pages (MAXY0).
9. A method according to claim 8, wherein the step E5 comprises
sub-steps E50 to E55 as follows: E50: the initialization of a
positive loop variable (SS_PAGE1=X0 or 1) and of a negative loop
variable (SS_PAGE2=X0 or 1), E52: the storage of the sub-page with
a rank equal to the positive loop variable, and the updating of the
counter and of the positive loop variable E55: if the negative loop
variable is greater than 0, then the storage of the sub-page with a
rank equal to the negative loop variable, followed by the updating
of the counter and the negative loop variable.
10. A storage device (10) comprising a data memory (12) to store a
teletext page comprising at least one sub-page, wherein the circuit
comprises a decoder (11) laid out to implement a method according
to one of the claims 1 to 9
11. A television receiver comprising a storage device according to
claim 10.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] An object of the invention is a method and an associated
device for the storage of teletext sub-pages and a television
receiver implementing said storage method. The present invention
relates more particularly to the field of teletext as defined in
the ETS (Enhanced Teletext Specification) No. 300 706 updated in
May 1997.
[0003] Teletext is an ancillary service of television stations
designed for the transmission, in addition to video information, of
written information in the form of digital data. A full teletext
service of a television station can be subdivided into a variable
number of pages (ranging from 100 to 899 according to the ETS
standard)
[0004] Each page can itself be subdivided into one or more
sub-pages (0 to 79 according to the ETS standard). All the
sub-pages of one and the same page form a consistent whole in terms
of informational content which it is preferable to consult in
chronological order, starting from the first sub-page. A full
service of a television station may thus comprise up to 71,000
sub-pages approximately and the whole service is broadcast
constantly and cyclically but not necessarily in chronological
order. Each sub-page is thus broadcast approximately every 40
seconds.
[0005] The digital data in a sub-page are assembled in the form of
data packets. One of the packets, often called a header packet,
comprises especially references of the sub-page to which it is
attached. These references are for example in the form "sub-page 5
of page 54", indicating the number or rank of the page (5) and the
number of the page to which it belongs (54).
[0006] 2. Description of the Prior Art
[0007] In existing navigation systems, which help a user of a
teletext service to identify the page that concerns him more or
less easily, the choice of a page is made for example by indicating
the number of the page requested. The movement between the
different sub-pages of one and the same page is then done by
"previous sub-page"/"next sub-page" type commands or else directly
by specifying the number of the sub-page.
[0008] In a television receiver, a device dedicated to the teletext
service comprises, according to FIG. 1, a decoder 11, a data memory
12, a display memory 13 and a display means 14.
[0009] The decoder 11 receives the digital data pertaining to the
sub-pages of the service and stores some of them in the data memory
12. When the user requests the display of a sub-page on a screen of
the television receiver, the decoder 11 copies the requested
sub-page from the data memory 12 in the display memory 13. Finally,
a display means 14 continually reads the contents of the display
memory 14 and copies them on a screen 15 of the television
receiver.
[0010] If the requested sub-page is already stored in the data
memory 12, then it is immediately displayed. If not, it takes much
longer for the display to be made because the decoder 11 must first
of all receive and then store the requested sub-page in the memory
12.
[0011] The number of sub-pages stored depends essentially on the
size of the data memory 12, which is highly variable from one
device to another. The number of sub-pages stored also depends on
the volume of digital data pertaining to each sub-page which may
vary from one sub-page to another.
[0012] The number of sub-pages that can be stored is, for example,
in the range of 10 to 15. This is a compromise between, firstly,
the mean display time of a requested page which diminishes when the
number of pages stored increases and, secondly, the cost of the
device which greatly increases with the size of the data memory
12.
[0013] The number of sub-pages stored is therefore limited as
compared with the total number of sub-pages or pages of a teletext
service. The decoder 11 manages the contents of the memory 12 as a
function of the sub-pages broadcast continually by the transmitter
station and of the user's requests. These are real or estimated
requests. They are estimated especially from the sub-pages being
displayed if a sub-page is being displayed.
[0014] Most frequently, the decoder 11 stores the sub-pages as and
when they are received. If the memory 12 is full, then the decoder
11 continues to store the sub-pages as and when they are received,
by erasing the previously stored sub-pages. Since only about 10
sub-pages are stored in the present example, the probability of the
sub-page being present in the memory when the user requests its
display is low. Consequently, the mean display time for a teletext
service sub-page is great.
[0015] The mean display time of the sub-page can be reduced by
storing a limited number of pages of the service and by storing one
or two sub-pages per page. The mean display time is diminished but
remains substantial because a page may contain a number of
sub-pages that varies between one and 80.
[0016] Furthermore, the order in which the sub-pages of the service
are broadcast as well at the total number of sub-pages broadcast
vary as a function of the day of the broadcast, the transmitter
station etc. Furthermore, if the device is activated during the
broadcasting of a teletext service, the first pages of the service
are received not immediately but only during the next broadcasting
cycle. Finally, it is difficult to foresee the sub-page that will
be contained in the memory 12 at a given point in time.
[0017] For all these reasons, when the user requests the display of
a sub-page of a service, the probability that this sub-page will be
already stored is low. Similarly, when the user requests the
display of a page comprising sub-pages, the probability that the
first-ranking sub-page will be stored is low. However, the sub-page
1 corresponds to the start of the information contained in the
page.
[0018] Consequently, with known devices and methods, the mean time
of display of a sub-page is relatively lengthy. Furthermore, it is
improbable that the beginning of the information will be directly
accessed during the display of a page. All this greatly limits the
value of known devices and of the teletext service for the
user.
SUMMARY OF THE INVENTION
[0019] It is a goal of the invention to reduce the mean display
time of the sub-page by increasing the probability of the sub-page
being already present in the memory when the user requests it.
[0020] Another object of the invention is to enable the user to
directly access the beginning of the information pertaining to a
teletext page.
[0021] With these goals in view, the invention relates to a method
for the storage of sub-pages of a teletext service comprising at
least one page to be stored, said page to be stored comprising at
least one sub-page, wherein:
[0022] a desired sub-page is stored, and
[0023] as the case may be, sub-pages neighboring the desired
sub-page are stored until a maximum number of stored sub-pages is
reached or until a limit number of sub-pages of the page to be
stored is reached.
[0024] The maximum number of sub-pages stored is defined by the
user or manufacturer of a television receiver using the method of
the invention. In practice, this number is directly related to the
size of the data memory used to store the pages of sub-pages. This
number for example is in the range of 2 to 3 if the size of the
data memory is sufficient to store 10 to 15 pages of sub-pages.
[0025] The limit number of sub-pages for a page is the total number
of sub-pages of one and the same page. It is variable and fixed by
the television station.
[0026] Furthermore, the expression "the neighboring sub-page" and
more generally the expressions "neighboring page", "nearby page",
"near" "close" etc. must be understood herein as follows: A page A
is said to be neighboring (or near) a page B if, when the page B is
displayed, there is a high probability that the user will requests
the display of the page A after having looked at the page B.
[0027] For example, the sub-pages ranked A+1 or A-1 are close to
the sub-page ranked A because the sub-pages of one and the same
page are most usually gone through in chronological order, by
virtue of their vary character of being sub-pages.
[0028] In the same spirit, the first-ranking sub-pages of all the
pages of the service are close to a higher-ranking sub-page and to
anyone of the pages of the service.
[0029] Thus, with the method of the invention, when a page is
stored, its sub-pages are stored only if they are near a desired
sub-page of said page to be stored. There is therefore a high
probability that, if a user requests the display of a sub-page,
this sub-page will already be stored. In this case, the display is
immediate. Thus, with the invention, the mean display time is
diminished as compared with known methods of storage.
[0030] According to one embodiment of the method of the invention,
the desired sub-page is a rank 1 sub-page of the page to be stored,
and the sub-pages neighboring the desired sub-page are the pages
with ranks closest to one.
[0031] Thus, when the user requests the display of a teletext page,
the rank 1 sub-pages immediately displayed. This rank 1 sub-page
corresponds to the beginning of the information contained in the
page, and the page may contain several sub-pages.
[0032] In this embodiment, the method is advantageously implemented
by performing the following steps:
[0033] E1: the initialization of a counter to count the number of
sub-pages stored,
[0034] E2: the storage of the rank 1 sub-page of the page to be
stored, and the updating of the counter,
[0035] E5: the storage of sub-pages neighboring the desired
sub-page and the updating of the counter, the step E5 being
repeated until the counter has reached a maximum number of stored
sub-pages.
[0036] The step E5 comprises for example the following
sub-steps:
[0037] E50: the initialization of a positive loop variable,
[0038] E52: the storage of the sub-page with a rank equal to the
positive loop variable, and the updating of the counter and of the
positive loop variable, the step 52 being repeated until the
maximum number of stored sub-pages is reached or until the limit
number of sub-pages of the page to be stored is reached.
[0039] This embodiment is for example used if the user has not
(yet) requested the display of a page. In this case, for the page
to be stored, the rank 1 sub-page (the desired sub-page), and the
pages ranked 2,3 etc close to the rank 1 sub-page are stored. The
user thus has very easy and immediate access to the information
contained in the page to be stored.
[0040] This embodiment may be chosen for example as a default
embodiment and may be used especially when no sub-page in
particular is requested by the user during the request for the
display of a page.
[0041] According to another embodiment, the desired sub-page is a
rank X0 sub-page requested by a user, and the sub-pages neighboring
the desired sub-pages are pages immediately preceding the desired
sub-page and/or sub-pages immediately following the desired
sub-page.
[0042] In this case, apart from the steps E1, E2, E5, the following
step E4 is carried out. It is executed before or after the step
E2:
[0043] E4: the storage of an X0 ranking desired sub-page of the
page to be stored, and the updating of the counter.
[0044] The step E5 is furthermore complemented by the step E55,
performed after or before the sub-step E52.
[0045] E55: if the negative loop variable is greater than 0, then
the storage of the sub-page with a rank equal to the negative loop
variable, followed by the updating of the counter and the negative
loop variable.
[0046] This embodiment is used for example when the X0 ranking
sub-page (the desired sub-page) of a page y0 (the page to be
stored) is being displayed at the user's request. In this case, the
sub-pages ranked X0, 1, X0+1, X0-1, etc are stored.
[0047] This is useful to the user owing to the very fact of the
structure of a page and of a teletext sub-page: the set of
sub-pages of one and the same page forms a consistent whole and the
informational content of the set must be read in the chronological
order of the sub-pages in order to be comprehensible. With the
invention, after having displayed the sub-page X0, the user has
very immediate and easy access to the neighboring pages X0+1, X0-1,
etc.
[0048] According to another embodiment, the teletext service
comprises several pages to be stored, each page comprising at least
one sub-page. For each page to be stored, a desired sub-page is
stored. This is either a rank 1 sub-page or a rank X0 sub-page
requested by the user. Furthermore, for each page to be stored,
sub-pages neighboring the desired sub-page are stored until a
maximum number of stored sub-pages of the page to be stored is
reached or until a limit number of sub-pages of the page to be
stored is reached.
[0049] It may be recalled that the maximum number of sub-pages
stored is defined by the user or the manufacturer of a television
receiver using the method of the invention. In practice, the number
is directly related to the size of the data memory used to store
the page of sub-pages. This number is for example in the range of
two to three if the size of the data memory is sufficient to store
10 to 15 pages or sub-pages.
[0050] The limit number of sub-pages for a page is the total number
of sub-pages of one and the same page. It is variable.
[0051] The invention also relates to a storage device comprising a
data memory to store a teletext page comprising at least one
sub-page, wherein the circuit comprises a decoder laid out to
implement a method as described here above.
[0052] Finally, the invention also relates to a television receiver
comprising a storage device such as the one described here
above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] The invention will be understood more clearly and other
features and advantages will appear from the following description
of an exemplary embodiment of the method and associated device of
the invention. The description refers to be appended figures, of
which:
[0054] FIG. 1 which has already been described is a functional
diagram of the device dedicated to the teletext service, according
to the prior art, and
[0055] FIGS. 2 and 3 are diagrams of algorithms for the
implementation of a storage method according to the invention.
MORE DETAILED DESCRIPTION
[0056] The storage method according to the invention is implemented
in a device dedicated to a teletext service similar to a known
device such as the one shown in FIG. 1. It has, in particular, a
data memory 12, a display memory 13 and a display means 14
identical to those of the known prior art and connected
similarly.
[0057] The device also has a novel decoder laid out to implement
the method for the storage of teletext sub-pages according to the
invention.
[0058] In the first exemplary implementation of the method, it is
assumed that the sub-page X0 of the page Y0 of the broadcast
teletext service is requested by a user and must therefore be
stored. It is also assumed that it is planned to store, at best, a
number MAXY0 of sub-pages of the page Y0, among them the rank 1
sub-page, the rank X0 sub-page and sub-pages neighboring the
sub-page X0. The user fixes X0, Y0.
[0059] For this first example, the steps of the method are
presented in FIG. 2.
[0060] During a step E1, a variable NB_SS_PGES is initialized at 0;
this variable is used to count the number of stored sub-pages and
verify that this number does not exceed the number MAXY0.
[0061] During a step E2, the rank 1 sub-page of page Y0 is stored
and the variable NB_SS_PGES is updated:
NB_SS_PGES=NB_SS_PGES+1.
[0062] Then, during a step E3, a test is performed to verify
whether the number of sub-pages already stored has not reached its
limit value MAXY0. If the value MAXY0 has been reached, then the
procedure is terminated. If not, the steps E4, E5 are carried
out.
[0063] During the next step E4, the rank X0 sub-page is stored and
the variable NB_SS_PGES is updated: NB_SS_PGES=NB_SS_PGES+1.
[0064] A step E5 is then carried out, to store the sub-pages
neighboring the sub-page X0. The step E5 can be subdivided as
follows:
[0065] During the step E50, two loop variables are initialized:
[0066] SS_PAGE=X0+1
[0067] SS_PAGE=X0-1
[0068] The variable SS_PAGE 1 is used to access the sub-pages
following the sub-page in progress: X0+1, X0+2, etc. The variable
SS_PAGE2 is used in the same way for the sub-pages preceding the
current sub-page X0-1, X0-2 etc.
[0069] During a following step E51, another test is performed to
verify whether the number of sub-pages already stored has not
reached its limit value MAXY0. If the value MAXY0 is reached, then
the step E5 is terminated. If not, a step E52 is carried out.
[0070] During the step E52, the SS_PAGE1 ranking sub-page is stored
and the variables SS_PAGE1 and NB_SS_PGES are updated:
[0071] SS_PAGE1=SS_PAGE1+1
[0072] NB_SS_PGES=NB_SS_PGES+1.
[0073] During a following step E53, which is identical to the step
E51, a test is performed. If the maximum number MAXY0 of sub-pages
to be stored is reached (negative test), then the step E5 is
terminated. If not, a step E54 is carried out.
[0074] During the test E54, it is verified whether the loop
variable SS_PAGE2 is positive. If the test is negative, then
another step 51 is carried out. If not, a step E55 is carried
out.
[0075] During the step E55, the SS_PAGE2 ranking sub-page is stored
and the variables SS_PAGE2 and NB_SS_PGES are updated:
[0076] SS_PAGE2=SS_PAGE2-1
[0077] NB_SS_PGES=NB_SS_PGES+1.
[0078] At the end of the step E55, a new step E51 is carried
out.
[0079] The method of FIG. 2 is terminated when the number of
sub-pages stored has reached its maximum value MAXY0 (when one of
the tests E3, E51 or E53 is negative).
[0080] The method of FIG. 2 is interrupted and then carried out
another time if the user requests the display of a new page or
sub-page.
[0081] In this example, the rank 1 sub-pages, X0+1, X0-1, X0+2,
X0-2 etc. are stored until the maximum number MAXY0 of sub-pages to
be stored is reached. The order in which the sub-pages are stored
depends especially on the order in which the sub-pages are received
by the decoder. The order in which the sub-pages are stored is
furthermore immaterial when the method of the invention is being
carried out. It may be modified, by exchanging the steps E2 and E4,
or else by performing the step E50 twice in succession, and then
the step E55 twice for example. What is essential is to store the
sub-page X0, the sub-page 1 and the sub-pages neighboring the
sub-page X0.
[0082] The rank X0 sub-page of page Y0 is displayed in parallel,
since it is requested by the user. If the user then wishes to have
the rest of the page Y0 that he is consulting, the display of the
next sub-page X0+1 will be immediate since it is already stored.
If, on the contrary, the user wishes to access the beginning of the
information contained in the page Y0, he will have very easy access
to the sub-page 1 of the page Y0 since the sub-page 1 has been
previously stored.
[0083] In a second exemplary implementation of the method of the
invention, it is assumed that the sub-pages of the page Y0 of a
teletext service must be stored although the user has not requested
the display of the page Y0 or of one of its sub-pages (for example
the user has requested the display of a page neighboring the page
Y0 or else no page is displayed). It is furthermore assumed that it
is planned to store, at best, a number MAXY0 of sub-pages of page
Y0. In this case, it is chosen to store the sub-page 1 of the page
Y0 and the sub-pages neighboring the sub-page 1.
[0084] In this example, the user has immediate access to the
sub-page 1 of the page Y0 if he has requested its display and the
sub-pages 2,3, 4 etc. are available. The user thus has direct
access to the beginning of the information contained in the page Y0
and he can consult the sub-pages of the page Y0 in chronological
order.
[0085] For this example, the method of FIG. 2 is modified as
follows:
[0086] the steps E3 any 4 are eliminated, the step E5 in this case
is performed after the step E2. This elimination is warranted
because the sub-step 1 is already stored during the step E2.
[0087] the step E50 is modified as follows:
[0088] SS_PAGE1=2
[0089] SS_PAGE2=0
[0090] the steps E53, E54, E55 are eliminated because they are
unnecessary. This is warranted by the fact that there is no
negative ranking sub-page.
[0091] In a third exemplary implementation of the method of the
invention, it is assumed that:
[0092] the sub-page X0 of the page Y0 is requested by the user, and
it must be stored in order to be displayed
[0093] the pages X0+1, X0-1, etc neighboring the sub-page X0 must
be stored.
[0094] the pages Y0+1, Y0-1 neighboring Y0 must also be stored. To
this end, for each page neighboring the page Y0, the sub-pages
1,2,3 etc must be stored.
[0095] The user thus has very fast access to the pages or sub-pages
closest to the sub-page that he has requested on the screen.
[0096] For this third example, the method of FIG. 3 is carried
out.
[0097] During a step E00, variables of pages and sub-pages are
initialized: X=X0 and Y=Y0.
[0098] During the following step E10, a step E10 for the storage of
sub-pages of the page Y=Y0 is carried out. The step E10 comprises
the set of steps E1 to E5 of the diagram of FIG. 2, and the step
E50 is simply modified as follows:
[0099] SS_PAGE1=X+1
[0100] SS_PAGE2=X-1
[0101] During the next step E20, the variable Y is updated: Y=Y0+1.
Then a new step E10 is performed to store the sub-pages of the page
Y=Y0+1.
[0102] The steps E10, E20 are repeated until all the pages and all
their desired sub-pages are stored and/or until the data memory is
saturated.
[0103] During the first execution of the step E11, the page Y0 is
stored, especially its rank 1 and rank X0 sub-pages, and the
sub-pages neighboring the rank X0 sub-page. During each following
execution of the step E10, a page neighboring the page Y0 is
stored, especially the sub-pages 1,2,3 etc of the page neighboring
the page Y0.
[0104] The method is interrupted and then executed again if the
user requests the display of a new page or a new sub-page.
[0105] Choice of pages to be stored:
[0106] In the third example (FIG. 3), the page Y0 and its
neighboring pages Y0+1, Y0-1,Y0+2, Y0-2 are stored with their
respective sub-pages.
[0107] However, it is possible to store other pages neighboring the
page Y0, for example the pages corresponding to blocks or groups of
pages as defined in the ETS standard, when a TOP navigation system
is used. For this purpose, it is enough to modify the step E20
accordingly to give the desired values to the variable Y. For
example, if Y0=125, Y may successively assume the values 100, 200,
300 etc., Y being modified at each execution of the step E20.
[0108] It is also possible to define a priority number for each
service page. This priority number is for example variable as a
function of the sub-page X0 of the page Y0 requested by the user. A
page or a sub-page has high priority if it is close to the page X0.
Conversely, a page or a sub-page has low priority if it is distant
from the sub-page X0.
[0109] Value of the number MAXY:
[0110] In the above examples, the number MAXY of sub-pages is
considered to be constant. However, it is possible to consider the
storage of a number of sub-pages that is variable as a function of
the stored page. It is enough, for this purpose, to modify the step
E1 to add an initialization of the number MAXY as a function of the
value of Y.
[0111] Stopping the step E5:
[0112] In the above examples given with reference to FIGS. 2, 3, it
has been implicitly assumed that one and the same page comprises a
number of sub-pages NB_LIMY greater than the chosen number MAXY.
However, this is not necessarily the case. For example, certain
service pages may comprise a reduced number NB_LIMY of sub-pages,
even just one sub-page.
[0113] In this case, the method is advantageously improved by
adding a complementary step E51', between the steps E51 and E52, to
test whether the variable SS_PAGE1 is smaller than the number
NB_LIMY of the page Y being stored. If SS_PAGE1 is smaller than
NB_LIMY, then the step E52 is carried out. If not, the step E54 is
carried out. NB_LIMY corresponds to the number of existing
sub-pages for one and the same given page Y.
[0114] Just like the number MAXY, the number NB_LIMY may be
variable from one page Y to another. In this case, it is preferably
initialized during the step E1.
[0115] Other modifications and/or improvements may be envisaged,
the essential point being that the following requirements should be
complied with:
[0116] if the display of a sub-page X0 of a page Y0 is requested by
the television viewer, then storage of the rank X0 sub-page, the
rank 1 sub-page, and sub-pages having ranks in the neighborhood of
X0, within the limit of a maximum number NB_SS_PGES=MAX(Y0) of
sub-pages stored for the page Y0 and/or within the limit of the
number of sub-pages NB_LIM of page Y0.
[0117] if no sub-page of the page Y0 is requested, then storage of
the rank 1 sub-page and sub-pages having ranks in the vicinity of 1
within the limit of a maximum number of pages NB_SS_PGES=MAX(Y0) of
sub-pages stored for the page Y0 and/or within the limit of the
number of sub-pages of the page Y0.
* * * * *